Method of communicating data in a wireless mobile communication system

ABSTRACT

A method of communicating data in a wireless communication system is disclosed. More specifically, a method discloses transmitting a request by a mobile subscriber station (MSS) to a network entity via a de-registration request message requesting the network entity to retain a preferred session information, and receiving a selected session information via a de-registration command response from the network entity.

This application claims the benefit of:

-   -   Korean Application No. P2004-048423, filed on Jun. 25, 2004;    -   Korean Application No. P2004-048618, filed on Jun. 26, 2004;    -   Korean Application No. P2004-053151, filed on Jul. 8, 2004;    -   Korean Application No. P2004-062984, filed on Aug. 2, 2004;    -   Korean Application No. P2004-063248, filed on Aug. 11, 2004; and    -   Korean Application No. P2005-005201, filed on Jan. 20, 2005,        which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of transmitting and receivingdata, and more particularly, to a method of communicating data in awireless mobile communication system.

2. Discussion of the Related Art

In a broadband wireless access system, a mobile subscriber station (MSS)is permitted to enter idle-mode to save power. The MSS in idle-mode doesnot need to perform handover procedure when moving between base stationsof a same paging zone. Normally, performing handover requires the MSS totransmit in the uplink direction during idle-mode. As a result of theMSS not having to transmit to the base station (BS), power can be saved.

A MSS is located in a paging group, comprised of a plurality of basestations. The coverage area which is covered by the paging group calleda paging zone. The base stations of the paging group in the paging zoneshare the same paging cycle and paging offset values.

The MSS transmits a request message to the BS requesting to enteridle-mode. The BS then sends a response message granting the MSS toenter idle-mode. In the response message, the BS includes paging groupidentification, paging cycle value, and paging offset value. The requestcan be made using a de-registration request (DREG-REQ) message.

In response to the request, the BS provides a response message to grantthe MSS to enter idle-mode. The response message includes paging groupidentification, paging cycle, and paging offset of the BS. The responsecan be made using a de-registration command (DREG-CMD) message.

In addition, the BS provides a medium access control (MAC) address ofthe MSS entering idle-mode to other BSs of the paging group so that theMSS can receive paging messages during idle-mode.

During idle-mode, the BS broadcasts at specified time intervals (alsoreferred to paging cycle) a message, inquiring whether the MSS wishes toremain in or terminate idle-mode or whether the MSS has to performranging operation. At the same time, the BS can transmit a pagingmessage to notify the MSS that there is downlink data for the MSS.

Idle-mode can be terminated by either the MSS or the BS. If the MSS hasto transmit data in the uplink direction, the MSS can terminateidle-mode anytime. On the other hand, if there is downlink traffic fromthe BS, the BS notifies the MSS to terminate idle-mode via a pagingmessage so that the MSS can receive data. Furthermore, if the MSS inidle-mode fails to receive the paging message from the BS at specifiedtime slot(s) or paging cycles for various reasons, such as moving toanother paging zone, the MSS terminates idle-mode.

Here, the MSS in idle-mode can freely roam within the boundary of thepaging zone without having to perform handover so long as the MSS doesnot have to receive any downlink traffic and/or transmit data in theuplink direction.

The MSS terminates idle-mode and re-registers/re-enters to the networkand received downlink data if it is notified via a paging message thatdownlink traffic exists from the BS. In addition, as part of performingranging operation, the MSS has the BS update the location of the MSS andan effective MSS information list. On the other hand, if the MSSreceives a command via a paging message not to perform any operation,the MSS remains in idle-mode.

However, if the MSS has to transmit data in the uplink direction or ifthe MSS moves to a different paging zone, the BS in the paging groupnotifies other BSs in the paging group that the MSS is no longer in thesame paging zone, thereby deleting the corresponding MSS from the listof MSSs in idle-mode.

If the MSS moves to another paging zone or need to transmit to the BSarises during idle-mode, the corresponding MSS terminates idle-mode andhas to register with the new BS of the new paging group. In registeringwith the new BS, the MSS has to go through the registration process fromthe beginning—the same registration process as the initial registrationprocess to the previous network. Therefore, the MSS expands much powerto register with the new network, and at the same time, much time isspent to go through the registration process.

In addition, if the MSS wishes to retain the idle-mode information ofthe previous paging group after moving to a new paging group, the MSShas to request idle-mode via a MAC control message after registeringwith the new network. Thereafter, the BS of the new paging groupprovides a response to the idle-mode request. Again, such procedurecauses increase in MAC signaling, thereby increasing use of power.

FIG. 1 illustrates the MSS terminating idle-mode and returning to normalmode to receive downlink traffic. Here, the MSS entered idle-mode per arequest made by the MSS to enter idle-mode. In addition, even if the MSSentered idle-mode per a command from the BS, the MSS terminatesidle-mode and returns to normal mode to receive downlink traffic.

Referring to FIG. 1, the MSS de-registers with a BS (BS1—host BS) viathe DREG-REQ and DREG-CMD (S10). After the MSS enters idle-mode, thehost BS notifies other BSs in the same paging group via pagingannouncement that the MSS has entered idle-mode (S11). In the pagingannouncement, the host BS includes a medium access control (MAC) addressof the MSS. Each BS receiving the paging announcement registers the MACaddress of the MSS in its paging list. This paging list is shared by allthe BSs in the paging zone.

While in idle-mode, data could be sent to the MSS. In order to receivethis data, the MSS must exit idle-mode. Hence, when downlink trafficexists, the host BS transmits a paging announcement to notify all theBSs in the paging group that data has to be delivered to the MSS (S12).Accordingly, each BS transmits a paging message to the MSS using the MACaddress provided from the host BS during paging intervals (S13).

The MSS receives the paging message from each BSs of the paging group.If an Action Code received from one of the BSs, i.e., BS#3, is set to“10, ” which indicates initial network entry, the MSS performs rangingoperation and initial network entry procedures with BS#3 (S14 and S15).Here, the ranging operation includes a ranging request (RNG-REQ) messagefrom the MSS and a ranging response (RNG-RSP) message from the BS. Afterthe MSS gains initial network entry, BS#3 transmits the downlink data tothe MSS (S16).

Saving power is not limited to idle-mode. As another means of savingpower besides idle-mode, the MSS can enter sleep mode to save power. Forthe MSS to enter sleep mode, the MSS transmits a request to enter sleepmode via a sleep request (MOB-SLP-REQ) message to the BS. The BS thensends a response message granting the MSS to enter sleep mode via asleep response (MOB-SLP-RSP) message. The MOB-SLP-REQ and MOB-SLP-RSPmessages includes various information such as the starting time of sleepmode, maximum/minimum sleeping interval (in frames), and listeninginterval(s).

At the end of the sleeping interval, the BS transmits a trafficindication (MOB-TRF-IND) message to notify the MSS of whether anydownlink traffic exists. If there is no downlink traffic for the MSS toreceive, the MSS can return to sleep mode. If, however, there isdownlink data, the MSS returns to normal mode to receive downlink data.

FIG. 2 illustrates the MSS terminating sleep mode and returning tonormal mode to receive downlink traffic. Here, the MSS entered sleepmode per a request made by the MSS to enter sleep mode. In addition,even if the MSS entered idle-mode per a command from the BS, the MSSterminates idle-mode and returns to normal mode to receive downlinktraffic.

Referring to FIG. 2, the MSS transmits a request to enter sleep mode viathe MOB-SLP-REQ message to the BS (S2-0). In response, the BS transmitsthe MOB-SLP-RSP message to the MSS (S2-1). In the MOB-SLP-RSP message,information such as the starting time of sleep mode (M), maximum/minimumsleeping interval (N1, N2), and listening interval (L1) are included.

The MSS enters sleep mode according to the minimum sleeping interval(N1) set in S20 and S21, and the BS transmits the MOB-TRF-IND messageduring the listening interval L1 (S2-2). It is through the MOB-TRF-INDmessage that the BS indicates the MSS whether there is any data toreceive for the MSS (negative/positive). In addition, the MSS listens orwakes up from sleeping during L1 to check whether any downlink dataexists. If there is no downlink data, which is indicated by ‘negativeindication,’ the MSS returns to sleep mode. However, after a listeninginterval, the sleeping interval or sleeping window size is doubledaccording to a scheduled sleep window setting method.

If the BS receives data to transmit to the MSS during the sleepinginterval, the BS stores the data in a specified storage space and waitsuntil the next listening interval, at which time the MSS is notified ofthe data via the MOB-TRF-IND message (S2-3). Thereafter, the MSS wakesup from sleep mode and returns to normal mode in order to receive data(S2-4).

In normal mode, if an internet protocol (IP) packet (data) is receivedby the MSS, a router transmits the IP packet to the MSS via a basestation. In version 4 of IP (IPv4), the router uses an ARP, and inversion 6 of IP (IPv6), the router uses neighbor discovery (ND). Inother words, when transmitting the IP packet to the MSS, the router usesthe ARP and ND protocols to find out a target link-layer address (e.g.,MAC address or Ethernet address) corresponding to the IP address of theMSS. The ARP is IPv4 protocol which is used when changing the IP addressto the link-layer address, such as the MAC address or Ethernet address.

Furthermore, the ND protocol is IPv6 address used to determine thelink-layer addresses of neighboring links. The changing of addressoccurs at the time when the IP packet header and the link-layer addressheader are generated. As such, the address change occurs only in theoutputted IP packet.

Traditionally, it is not clearly specified as to how the BS transmits orbroadcasts the request or neighboring solicitation to the MSS. Morespecifically, the specific role or operation by the BS has not beenclearly defined in transmitting the request/neighboring solicitation tothe MSS during normal mode.

Furthermore, the MSS in either sleep mode or idle-mode only receivessignal at specified intervals/cycles. As a result, if the router has totransmit a received data to the MSS, a problem arises when the MSS is insleep mode or idle-mode since the MSS cannot respond to the ARP requestor neighboring solicitation until the scheduled time. Consequently, thetarget MSS cannot send a response, resulting in delivery failure. Basedon the problem, it is possible that the MSS does not receive the data.

As discussed above, the problem exists in delivering data to the MSSfrom the router. Especially since in power saving sleep-mode oridle-mode of the MSS, the data received at the router cannot be receivedby the MSS since the MSS cannot receive until specified times.Therefore, the data is not always transmitted to the MSS.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method ofcommunicating data in a wireless broadband communication system thatsubstantially obviates one or more problems due to limitations anddisadvantages of the related art.

An object of the present invention is to provide a method ofcommunicating data between the MSS and a network entity to enteridle-mode, update location during idle-mode, and re-enter network afteridle-mode.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod of communicating data for entering idle-mode includes the MSStransmitting a request by a mobile subscriber station (MSS) to a networkentity via a de-registration request message requesting the networkentity to retain a preferred session information, and receiving aselected session information via a de-registration command response fromthe network entity.

In another aspect of the present invention, a method for updatinglocation of the MSS which includes transmitting a request to a secondnetwork entity via a ranging request message requesting a locationupdate of the MSS from a first network entity, receiving a selectedsession information to be updated via a response message from the secondnetwork entity, and performing network entry procedure to update sessioninformation after the location of the MSS is updated from the firstnetwork entity to the second network entity.

In another aspect of the present invention, a method for enteringnetwork after idle-mode. More specifically, the method includestransmitting a request to a second network entity via a ranging requestmessage, receiving a selected session information via a ranging responsemessage from a second network entity, wherein the selected sessioninformation is received by the second network entity from a firstnetwork entity, and entering a network of the second network entity.

In another aspect of the present invention, a method requesting anetwork entity to retain network address of the MSS is introduced. Theprocess includes transmitting to a first network entity a request toretain a network address via a request message, entering idle-mode afterreceiving a response message from the first network entity, receiving apaging message from a second network entity during idle-mode, entering anetwork of the second network entity, and receiving an internet protocol(IP) packet from the second network entity.

In another aspect of the present invention, a method requesting anetwork entity to retain convergence sublayer information is introduced.The process includes transmitting via a request message a request to afirst network entity to retain a convergence sublayer (CS) information,entering idle-mode after receiving a response message from the firstnetwork entity, receiving a paging message from a second network entityduring idle-mode, entering network of the second network, and receivinga data packet from the second network entity.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings;

FIG. 1 illustrates a mobile subscriber station (MSS) terminatingidle-mode and returning to normal mode to receive downlink traffic;

FIG. 2 illustrates the MSS terminating sleep mode and returning tonormal mode to receive downlink traffic;

FIG. 3 illustrates a signaling process when MSS bound downlink trafficarises during idle-mode;

FIG. 4 illustrates a signaling process when the MSS requests to enteridle-mode and requests the network entity to retain session information;

FIG. 5 illustrates a signaling process when the network entity commandsthe MSS to enter idle-mode, and the MSS requests the network entity toretain session information;

FIG. 6 illustrates a signaling process of location update by the MSSfrom one paging group to another paging group;

FIG. 7 illustrate a link-layer address acquisition process of a routerwhen the MSS voluntarily enters sleep mode;

FIG. 8 illustrates a link-layer address acquisition process of a routerwhen the MSS enters sleep mode as a result of command from the networkentity;

FIG. 9 illustrates a link-layer address acquisition process of a routerwhen the MSS voluntarily enters idle-mode;

FIG. 10 illustrates a link-layer address acquisition process of a routerwhen the MSS enters sleep mode as a result of command from the networkentity;

FIG. 11 illustrates another embodiment of a link-layer addressacquisition process of a router when the MSS voluntarily entersidle-mode; and

FIG. 12 illustrates a link-layer address acquisition process of a routerwhen the MSS enters sleep mode as a result of command from the networkentity.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

When entering idle-mode, the MSS transmits to a network entity sessioninformation of the MSS via a request message. The network entity can bea base station, paging controller, access gateway, or base stationcontroller, for example. The session information is a list of sessioninformation of the MSS which the MSS prefers that the network entityretain. Particularly, a MSS preferred session information relates tonetwork re-entry related services and operational information toexpedite future network re-entry from idle-mode.

In addition, the request message includes a request by the MSS to enteridle-mode. For example, the request message is a de-registration request(DREG-REQ) message. Furthermore, the request message includes thepreferred session information which the MSS desires the network entityretain. More specifically, the session information includes informationsuch as security information, internet protocol (IP) addressinformation, the MSS capability, management connection identification,and information essential to maintaining network service.

After receiving the preferred session information (or sessioninformation list), the network entity selects session information whichit decides to retain. Thereafter, the network entity notifies the MSSvia a response message of the network entity selected sessioninformation. The selected session information can be same, different, orcombination thereof from the preferred session information transmittedfrom the MSS. Again, the selected session information comprises a listof network entity selected session information to expedite a future MSSre-entry from idle-mode by retaining certain MSS service and operationalinformation. Furthermore, the selected session information is used toensure effective and efficient service flow between the MSS and thenetwork entity.

In addition, the response message includes a response to the request bythe MSS to enter idle-mode. For example, the request message is ade-registration command (DREG-CMD) message. In the response message, thenetwork entity includes the selected session information.

During idle-mode, if there is downlink traffic to the MSS, the networkentity transmits a paging message, and included in the paging message isthe selected session information, to the MSS receiving the downlinkdata. Usually, the paging message can be transmitted periodically or atspecified time intervals. Thereafter, the network entities in the samepaging group share with each other the selected session information viaa backbone network. As a result, when the MSS terminates idle-mode andre-enters the network, the MSS can bypass some of the procedural stepsrequired in re-entering the network. As explained earlier, retention ofthe selected session information by the network entity makes possibleexpedited re-entry. The procedural steps include, for example, thosesteps than can be shared concurrently with other network entities suchas the IP address and/or security information.

In the event the MSS moves to another paging group and requires alocation update, a new network entity in another paging group receivesthe selected session information from the network entity of the previouspaging group. The network entity of the previous paging group is thenetwork entity which retained the latest updated MSS sessioninformation. The new network entity of another paging group thentransmits the selected session information received from the previouspaging group to the MSS. Subsequently, in updating the location of theMSS, the MSS re-enters the new network in order to update information.In short, the location update of the MSS can take place in paging zoneidentification based environment where the updating occurs when the MSSmoves from one paging zone identification to another paging zoneidentification, for example.

In addition, location update of the MSS can take place based on time. Inother words, timer-based location update includes a schedule whereby theMSS and network conducts location update. For example, if a timer-basedlocation update schedule is set at every 10 seconds between the MSS andthe network entity, location of the MSS is updated every 10 secondsbased on previous location update regardless whether the MSS have movedor not.

When the MSS receives a plurality of paging group identifications viathe paging message, the MSS requests for a location update to thecorresponding network entity. In updating the location, the MSStransmits to the network entity the identification of the network entitywhich granted idle-mode entry in the previous paging group and thepaging group identification of the paging group which wishes to permitthe MSS to remain in idle-mode. Thereafter, the corresponding networkentity transmits information, such as the paging group identification,the paging cycle value, and the paging offset value, via the responsemessage to the location update request, to permit the MSS to remain inidle-mode after moving to a different paging group.

The following Table 1 shows an example of message parameter of thesession information list of the MSS.

TABLE 1 Name Type Length Value Expedited nn 1 For each Bit location, avalue of ‘0’ Network indicates the associated re-entry Setup managementmessages are not wished to be kept, a value of ‘1’ indicated the reentrymanagement messages are wished to be kept. Bit#0: SBC-REQ/RSP managementrelated profiles Bit#1: PKM-REQ/RSP management related profiles Bit#2:REG-REQ/RSP management related profiles Bit#3: Network AddressInformation related profiles Bit#4: Network Service related profilesBit#5~6: reserved

The message parameter of Table 1 is included in the message in the TLVformat, and the network registration procedure that can be bypassed whenterminating idle-mode can be expressed in a bit map format. In theembodiments of the present invention, such operation is indicated as“Expedited network setup_flag.”

FIG. 3 illustrates an embodiment of the present invention with respectto a signaling process when MSS bound downlink traffic arises duringidle-mode. The FIG. 3 shows the procedures for the MSS to terminateidle-mode when downlink traffic exists.

The MSS transmits to a first network entity a request message to requestto enter idle-mode via a de-registration request (DREG-REQ) message(S10). Included in the request message is a MSS preferred sessioninformation which the MSS prefers that the network entity retain forexpedited future re-entry to a network. As explained above, the networkentity can be a base station, paging controller, access gateway, or abase station controller, for example. This MSS preferred sessioninformation includes information such as security information, internetprotocol (IP) address information, the MSS capability, managementconnection identification, and information essential to maintainingnetwork service. The preferred session information message can be in aformat similar to that of Table 1.

For the sake of explaining, the network entity, which received thepreferred session information from the MSS, is identified as a firstnetwork entity. Also, a second network entity can be identified as anetwork entity which the MSS seeks to re-enter from idle-mode. Afterreceiving the request message, the first network entity broadcasts viabackbone channel(s) a notification to at least one or all other networkentities having the same paging identifications in the paging group sothat the corresponding MSS can be added to each network entity in thepaging group (S20). Thereafter, in response to the request message, thefirst network entity transmits a selected session information to thecorresponding MSS via a de-registration response command (DREG-CMD)(S30). The selected session information includes certain MSS service andoperational information useful for expediting a future MSS networkre-entry from idle-mode. The selected session information can be a listof selected session information which can be same, different, orcombination thereof as the preferred session information requested bythe MSS. Moreover, in the transmission of the DREQ-CMD, otherinformation such as paging cycle, paging offset, and pagingidentification can be included. The DREG-CMD is a command or a messagegranting the MSS to enter idle-mode as requested.

Upon receipt of the DREG-CMD from the first network entity, the MSSenters idle-mode. During idle-mode, the MSS can receive a pagingmessage(s) at specified time slots or intervals from the first networkentity (S40). The paging message includes various information such aswhether there is any downlink traffic or when to terminate idle-mode.

During idle-mode, it is possible for the MSS to move to another networkentity (hereinafter “second network entity”) in a paging group havingsame paging group identifications or in a paging group having aplurality of paging group identifications. If the MSS moves to thesecond network entity within the same paging group which has the samepaging identification (S50), the MSS receives paging message(s) from thesecond network entity at same paging cycle and paging offset as receivedfrom the first network entity (S60).

When downlink traffic arrives to the first network entity, and the firstnetwork entity is notified of downlink traffic to the MSS (S70), thefirst network entity transmits the session information along withexistence of downlink traffic via a backbone network to other networkentities in the paging group (S80).

After receiving the selected session information from the first networkentity, the second network entity transmits a paging message, includingthe selected session information and existence of downlink traffic, tothe MSS (S90). The MSS then transmits the identification of the firstnetwork entity, which granted the MSS to enter idle-mode, to the secondnetwork entity via a ranging request message (S100).

Upon receipt of the identity of the first network entity, the secondnetwork entity notifies the first network entity that the MSS is locatedin its coverage area and requests the first entity to transmit thesession information of the corresponding MSS retained by the firstnetwork entity (S110).

The first network entity complies with the request by transmitting theretained session information via the backbone channels (S120).Furthermore, the second network entity transmits to the MSS the list ofsession information currently retained by the second network entity viaa ranging response message (S130). As a result, when the MSS performsre-entry to the network, certain procedural steps required for re-entryto the network can be skipped. In other words, because the secondnetwork entity retains certain MSS service and operational information,the same information is not required in re-entry to the network. At thesame time, the MSS receives via the ranging response message theprocedural steps that can be skipped by the MSS in re-entering thenetwork.

Based on the information provided from the second network entity,network entry or re-entry procedure takes place (S140). The proceduralsteps of the network registration can include, for example, thenegotiation procedure of the MSS capability, security procedure,registration procedure, IP address acquisition procedure, to name a few.In addition, in order to establish connection for data reception, theMSS carries out the necessary procedures in conjunction with the networkentry procedures. After procedures for network entry (or re-entry) anddata reception are completed, the second network entity transmits thedownlink data received from the first network to the MSS (S150).

The steps (S10-S150) describe the operation in the network when downlinktraffic exists during idle-mode. If uplink traffic occurs to the MSS inidle-mode, certain steps (S70, S80, S90, and S150) can be excluded fromoperation.

FIG. 4 illustrates a signaling process when the MSS requests to enteridle-mode and requests the network entity to retain session information.As another embodiment of the present invention, the processes involvedin updating the location of the MSS in idle-mode after the MSS moves toanother paging group is described.

Referring to FIG. 4, the MSS transmits a request message to request to afirst network entity to enter idle-mode via a de-registration request(DREG-REQ) message (S210). Included in the request message is a MSSpreferred session information which the MSS prefers that the networkentity retain for expedited future re-entry to a network. The networkentity can be a BS or a paging controller. As explained above, thenetwork entity can be a base station, paging controller, access gateway,or a base station controller, for example. This MSS preferred sessioninformation includes information such as security information, internetprotocol (IP) address information, the MSS capability, managementconnection identification, and information essential to maintainingnetwork service. The preferred session information message can be in aformat similar to that of Table 1.

As explained above, the identities of a first network entity and asecond network entity are described with respect to FIG. 3. Afterreceiving the request message, the first network entity broadcasts via abackbone channel a notification to all other network entities having thesame paging identifications in the paging group so that thecorresponding MSS can be added to each network entity in the paginggroup (S220). Thereafter, in response to the request message, the firstnetwork entity transmits a selected session information to thecorresponding MSS via a de-registration response command (DREG-CMD)(S230). The selected session information includes certain MSS serviceand operational information useful for expediting a future MSS networkre-entry from idle-mode. The selected session information can be a listof selected session information which can be same, different, orcombination thereof as the preferred session information requested bythe MSS. Moreover, in the transmission of the DREQ-CMD, otherinformation such as paging cycle, paging offset, and pagingidentification can be included. The DREG-CMD is a command or a messagegranting the MSS to enter idle-mode as requested.

Upon receipt of the DREG-CMD from the first network entity, the MSSenters idle-mode. During idle-mode, the MSS can receive a pagingmessage(s) at specified time slots or intervals from the first networkentity (S240). The paging message includes various information such aswhether there is any downlink traffic or when to terminate idle-mode.

During idle-mode, it is possible for the MSS to move to another networkentity (hereinafter “second network entity”) in a paging group havingsame paging group identifications or in a paging group having aplurality of paging group identifications. If the MSS moves to thesecond network entity within the same paging group which has the samepaging identification (S250), the MSS receives paging message(s) fromthe second network entity at same paging cycle and paging offset asreceived from the first network entity (S260).

If the cell coverage area is designed so that a network entity can onlybelong one paging group, a network entity moving to a paging grouphaving more than one paging group identifications refers to the networkentity in transit between two paging groups, for example.

It is at this point the MSS learns that second network entity alsobelongs to a second paging group which has different paging groupidentification than that of the first paging group. The second networkentity transmits a paging group identification corresponding to thepaging group to which it belongs via a paging message. If the cellcoverage area is designed so that a network entity can belong only toone paging group, it is possible to transmit a paging groupidentification of a neighboring paging group, for example.

After receiving a paging message having different paging groupidentification, the MSS requests for location update from the secondnetwork entity via a ranging request message (S270). In addition tolocation update request, the ranging request message can include otherinformation such as the identification of the first network entity,which granted the MSS to enter idle-mode, the paging groupidentification of a second paging group, and a desired paging cycle. Ifthe cell coverage area is designed so that a network entity can belongonly to one paging group, the MSS cannot receive the paging message viaprevious paging information when the MSS moves to another paging group,so it is at this point the MSS requests for location update to a newnetwork entity, for example.

The second network entity, after receiving a location update requestfrom the MSS, makes a request to the first network entity to transmitthe selected session information currently retained by the first networkentity (S280). The first network entity then transmits the currentlyretained selected session information to the second network entity perrequest (S290).

Even after the location of the MSS has been updated, the second networkentity transmits the list of retained session information of the MSS viaa ranging response message (S300). Here in the ranging response message,other information such as a second paging group identification andcorresponding paging cycle and paging offset values. As a result, thecorresponding MSS is able to receive the paging message according to thesecond paging group identification. Furthermore, the second networkentity transmits to the MSS the session information currently retainedby the second network entity via a ranging response message. As aresult, when the MSS performs re-entry to the network, certainprocedural steps required for re-entry to the network can be skipped. Inother words, because the second network entity retains certain MSSservice and operational information, the same information is notrequired in re-entry to the network. At the same time, the MSS receivesvia the ranging response message the procedural steps that can beskipped by the MSS in re-entering the network.

After receiving the retained session information from the first networkentity via the ranging response message, the MSS can execute necessarynetwork entry procedure(s) in order to update no longer effective oroutdated information (S310). The second network entity uses a backbonenetwork to notify the other network entities of the first paging groupthat the MSS has relocated to a different paging group and tode-register and delete information related to the MSS (S320). At thesame time, the second network entity notifies the network entities ofthe second paging group to add information related to the MSS via thebackbone network. As for the MSS, the MSS receives paging messages atspecified intervals from the second paging group and maintains idle-mode(S330).

As described above, if the location of the MSS is updated from a firstnetwork entity to a second network entity, downlink data directed to theMSS is received by the second network entity, which has updated thelocation of the MSS, and not the first network entity.

FIG. 5 illustrates a signaling process of another embodiment of thepresent invention. Here, downlink traffic exists in an environment wherea MSS enters idle-mode as a result of a command by a network entity tothe MSS to enter idle-mode via a de-registration command (DREG-CMD)message.

In this embodiment, the network entity commands the MSS to enteridle-mode unlike the previous embodiments where the MSS transmitted arequest to the network entity to enter idle-mode. Here, the command toenter idle-mode is transmitted via the DREG-CMD message. The DREG-CMDincludes an action code set at 0×05 and a required duration(REQ-duration) which specifies time for the MSS to enter idle-mode(S410).

More specifically, a first network entity requests the MSS to transmit aMSS preferred session information via the DREG-CMD message. The DREG-REQincludes a specified time by or at which the MSS transmits the requestedmessage. After the receiving the DREG-CMD from the first network entity,the MSS transmits the network entity the requested MSS preferred sessioninformation at the specified time to the first network via ade-registration request (DREG-REQ) message (S420). The MSS preferredsession information includes information such as security information,internet protocol (IP) address information, the MSS capability,management connection identification, and information essential tomaintaining network service. The MSS preferred session information is alist of session information which the MSS prefers that the networkentity retain for expedited future re-entry to a network.

As explained above, the identities of a first network entity and asecond network entity are described above with respect to FIG. 3. Afterreceiving the request message, the first network entity broadcasts viabackbone channel(s) a notification to all other network entities havingthe same paging identifications in the paging group so that thecorresponding MSS can be added to each network entity in the paginggroup (S430). Thereafter, in response to the request message, the firstnetwork entity transmits a selected session information to thecorresponding MSS via a de-registration response command (DREG-CMD)(S440). The selected session information includes certain MSS serviceand operational information useful for expediting a future MSS networkre-entry from idle-mode. The selected session information can be a listof selected session information which can be same, different; orcombination thereof as the preferred session information requested bythe MSS. Moreover, in the transmission of the DREQ-CMD, otherinformation such as paging cycle, paging offset, and pagingidentification can be included. The DREG-CMD is a command or a messagegranting the MSS to enter idle-mode as requested.

Upon receipt of the DREG-CMD from the second network entity, the MSSenters idle-mode. During idle-mode, the MSS can receive a pagingmessage(s) at specified time slots or intervals from the first networkentity (S450). The paging message includes various information such aswhether there is any downlink traffic or when to terminate idle-mode.

During idle-mode, it is possible for the MSS to move to another networkentity (hereinafter “second network entity”) in a paging group havingsame paging group identifications or in a paging group having aplurality of paging group identifications. If the MSS moves to thesecond network entity within the same paging group which has the samepaging identification (S460), the MSS receives paging message(s) fromthe second network entity at same paging cycle and paging offset asreceived from the first network entity (S470).

When downlink traffic arrives to the first network entity, and the firstnetwork entity is notified of downlink traffic to the MSS (S480), thefirst network entity transmits the session information along withexistence of downlink traffic via a backbone network to other networkentities in the paging group (S490). Here, the selected sessioninformation transmitted to other network entities in the paging groupvia the backbone channels can be a list of selected session information.

After receiving the selected session information from the first networkentity, the second network entity transmits a paging message, includingthe selected session information and existence of downlink traffic, tothe MSS (S500). The MSS then transmits the identification of the firstnetwork entity, which granted the MSS to enter idle-mode, to the secondnetwork entity via a ranging request message (S510).

Upon receipt of the identity of the first network entity, the secondnetwork entity notifies the first network entity that the MSS is locatedin its coverage area and requests the first entity to transmit thesession information of the corresponding MSS retained by the firstnetwork entity (S520).

The first network entity complies with the request by transmitting theretained session information via the backbone channels (S530).Furthermore, the second network entity transmits to the MSS the list ofsession information currently retained by the second network entity viaa ranging response message (S540). As a result, when the MSS performsre-entry to the network, certain procedural steps required for re-entryto the network can be skipped. In other words, because the secondnetwork entity retains certain MSS service and operational information,the same information is not required in re-entry to the network. At thesame time, the MSS receives via the ranging response message theprocedural steps that can be skipped by the MSS in re-entering thenetwork.

Based on the information provided from the second network entity,network entry or re-entry procedure takes place (S550). The proceduralsteps of the network registration can include, for example, thenegotiation procedure of the MSS capability, security procedure,registration procedure, IP address acquisition procedure, to name a few.In addition, in order to establish connection for data reception, theMSS carries out the necessary procedures in conjunction with the networkentry procedures. After procedures for network entry (or re-entry) anddata reception are completed, the second network entity transmits thedownlink data received from the first network to the MSS (S560).

The steps (S410-S560) describe the operation in the network whendownlink traffic exists during idle-mode. If uplink traffic occurs tothe MSS in idle-mode, certain steps (S480, S490, S500, and S560) can beexcluded from operation.

FIG. 6 illustrates a signaling process of another embodiment of thepresent invention. Here, downlink traffic exists in an environment wherea MSS enters idle-mode as a result of a command by a network entity tothe MSS to enter idle-mode via a de-registration command (DREG-CMD)message. In addition, this embodiment describes the processes involvedin updating the location of the MSS in idle-mode after the MSS moves toanother paging group.

In this embodiment, the network entity commands the MSS to enteridle-mode unlike the previous embodiments where the MSS transmitted arequest to the network entity to enter idle-mode. Here, the command toenter idle-mode is transmitted via the DREG-CMD message. The DREG-CMDincludes an action code set at 0×05 and a required duration(REQ-duration) which specifies time for the MSS to enter idle-mode(S610).

More specifically, a first network entity requests the MSS to transmit aMSS preferred session information via the DREG-CMD message. The DREG-REQincludes a specified time by or at which the MSS transmits the requestedmessage. After the receiving the DREG-CMD from the first network entity,the MSS transmits the network entity the requested MSS preferred sessioninformation at the specified time to the first network via ade-registration request (DREG-REQ) message (S620). The MSS preferredsession information includes information such as security information,internet protocol (IP) address information, the MSS capability,management connection identification, and information essential tomaintaining network service. The MSS preferred session information is alist of session information which the MSS prefers that the networkentity retain for expedited future re-entry to a network.

As explained above, the identities of a first network entity and asecond network entity are described above with respect to FIG. 3. Afterreceiving the request message, the first network entity broadcasts viabackbone channel(s) a notification to all other network entities havingthe same paging identifications in the paging group so that thecorresponding MSS can be added to each network entity in the paginggroup (S630). Thereafter, in response to the request message, the firstnetwork entity transmits a selected session information to thecorresponding MSS via a de-registration response command (DREG-CMD)(S640). The selected session information includes certain MSS serviceand operational information useful for expediting a future MSS networkre-entry from idle-mode. The selected session information can be a listof selected session information which can be same, different, orcombination thereof as the preferred session information requested bythe MSS. Moreover, in the transmission of the DREQ-CMD, otherinformation such as paging cycle, paging offset, and pagingidentification can be included. The DREG-CMD is a command or a messagegranting the MSS to enter idle-mode as requested.

Upon receipt of the DREG-CMD from the first network entity, the MSSenters idle-mode. During idle-mode, the MSS can receive a pagingmessage(s) at specified time slots or intervals from the first networkentity (S650). The paging message includes various information such aswhether there is any downlink traffic or when to terminate idle-mode.

During idle-mode, it is possible for the MSS to move to another networkentity (hereinafter “second network entity”) in a paging group havingsame paging group identifications or in a paging group having aplurality of paging group identifications. If the MSS moves to thesecond network entity within the same paging group which has the samepaging identification (S660); the MSS receives paging message(s) fromthe second network entity at same paging cycle and paging offset asreceived from the first network entity (S670).

If the cell coverage area is designed so that a network entity can onlybelong one paging group, a network entity moving to a paging grouphaving more than one paging group identifications refers to the networkentity in transit between two paging groups, for example.

It is at this point the MSS learns that second network entity alsobelongs to a second paging group which has different paging groupidentification than that of the first paging group. The second networkentity transmits a paging group identification corresponding to thepaging group to which it belongs via a paging message. If the cellcoverage area is designed so that a network entity can belong only toone paging group, it is possible to transmit a paging groupidentification of a neighboring paging group, for example.

After receiving a paging message having different paging groupidentification, the MSS requests for location update from the secondnetwork entity via a ranging request message (S680). In addition tolocation update request, the ranging request message can include otherinformation such as the identification of the first network entity,which granted the MSS to enter idle-mode, the paging groupidentification of a second paging group, and a desired paging cycle. Ifthe cell coverage area is designed so that a network entity can belongonly to one paging group, the MSS cannot receive the paging message viaprevious paging information when the MSS moves to another paging group,so it is at this point the MSS requests for location update to a newnetwork entity, for example.

The second network entity, after receiving a location update requestfrom the MSS, makes a request to the first network entity to transmitthe selected session information currently retained by the first networkentity (S690). The first network entity then transmits the currentlyretained selected session information to the second network entity perrequest (S700).

Even after the location of the MSS has been updated, the second networkentity transmits the retained session information of the MSS via aranging response message (S710). Here in the ranging response message,other information such as a second paging group identification andcorresponding paging cycle and paging offset values. As a result, thecorresponding MSS is able to receive the paging message according to thesecond paging group identification. Furthermore, the second networkentity transmits to the MSS the session information currently retainedby the second network entity via a ranging response message. As aresult, when the MSS performs re-entry to the network, certainprocedural steps required for re-entry to the network can be skipped. Inother words, because the second network entity retains certain MSSservice and operational information, the same information is notrequired in re-entry to the network. At the same time, the MSS receivesvia the ranging response message the procedural steps that can beskipped by the MSS in re-entering the network.

After receiving the retained session information from the second networkentity via the ranging response message, the MSS can execute necessarynetwork entry procedure(s) in order to update no longer effective oroutdated information (S720). The second network entity uses a backbonenetwork to notify the other network entities of the first paging groupthat the MSS has relocated to a different paging group and tode-register and delete information related to the MSS (S730). At thesame time, the second network entity notifies the network entities ofthe second paging group to add information related to the MSS via thebackbone network. As for the MSS, the MSS receives paging messages atspecified intervals from the second paging group and maintains idle-mode(S740).

As described above, if the location of the MSS is updated from a firstnetwork entity to a second network entity, downlink data directed to theMSS is received by the second network entity, which has updated thelocation of the MSS, and not the first network entity.

The above discussions relate to operations/procedures of the MSS and thenetwork entities in entering network(s) for idle-mode, includingupdating session information to expedite re-entry of the MSS fromidle-mode. The following discusses the operations of the MSS beforeentering idle-mode in order to effectively receive downlink trafficduring idle-mode.

During normal mode, a router uses a destination or target IP address tofind out a MSS link-layer address (e.g., MAC address or Ethernetaddress) in order to transmit data to the MSS. To accomplish this, therouter sends an address request to the network entity. Here, in version4 of the IP (IPv4), the router transmits the ARP request, and in version6 of the IP (IPv6), the router transmits neighboring solicitation.

In an embodiment of the present invention, after the network entityreceives the address request message from the router, the network entitybroadcasts to a plurality MSSs or transmits the address request messageto each MSS individually. Thereafter, the network entity receives theresponse messages from the MSSs, such as an ARP response message orneighbor advertisement response message, and transmits the responsemessage to the router. In the address request message, for example, theMAC address or the Ethernet address can be included. From the pluralityof the MSSs who received the address request message, the MAC orEthernet address of a MSS can match the MAC or Ethernet address includedin the address request message. Then the MSS having the matching MACaddress transmits a response message to the network entity via asecondary management connection or a general data burst.

Furthermore, in an embodiment of the present invention, a network entitycan transmit to a router a proxy ARP response message (or proxy neighboradvertisement) of a MSS in sleep/idle-mode. In other words, the networkentity can respond directly to a request by the router as an agent ofthe MSS, for example. For the network entity to respond to the router,the MSS includes its IP address in the MOB-SLP-REQ message or theDREG-REQ message and transmits to the network entity. In addition, theMSS provides its IP address to the network entity before enteringsleep/idle-mode when entry to sleep/idle-mode is ordered by the networkentity. The embodiment of the present invention is not limited to IPv4but can apply to IPv6 using neighbor discovery protocol.

In the embodiment of the present invention, the network entity uses aproxy ARP or a proxy neighbor discovery protocol to have datatransmitted to the network entity while the MSS is in sleep mode oridle-mode. As discussed earlier, the network entity can be a basestation, paging controller, access gateway, or a base stationcontroller. In the figures, a base station (BS) is used as an example ofa network entity to describe the embodiments. In the previousembodiment, the network entity transmitted the ARP or neighbordiscovery-related messages to the MSS. In the process, the data couldfail to reach the destination MSS if the MSS was in sleep or idle-mode.However, in this embodiment, the network entity can respond directly tothe ARP request or neighbor solicitation from the router. To this end,the network entity has to possess the IP address and the link-layeraddress (MAC address or Ethernet address) of the MSS.

To possess the addresses, the network entity can acquire the MSS IPaddress and the link-layer address when the MSS registers with thenetwork entity to enter sleep mode or idle-mode or by searching the MSSIP address setting. More specifically, the network entity can acquirethe IP address by receiving directly from the MSS the IP address whenthe MSS transmits the IP address via a request message. In addition, thenetwork entity can acquire the IP address by the MSS requesting thenetwork entity to use the IP address currently retained in the networkentity. In other words, the MSS does not transmit an IP address andmaintains its IP address retained in the network entity. The networkentity can also acquire the information by making a direct request tothe MSS for the IP and link-layer addresses.

FIG. 7 illustrates a link-layer address acquisition process of a routerwhen the MSS voluntarily enters sleep mode. Referring to FIG. 7, the MSStransmits a MOB-SLP-REQ message to the network entity to request toenter sleep mode (S3-0). In the request message, the MSS includes its IPaddress to allow the network entity to respond to possible future ARPrequests from the router. In response to the request, the network entitytransmits the MOB-SLP-RSP message to the MSS (S3-1).

Upon receiving the response message from the network entity, the MSSenters sleep mode for duration specified in the MOB-SLP-RSP message.After the sleeping interval, the MSS wakes up for listening interval(L1) to receive the MOB-TRF-IND message from the network entity anddetermine whether there is any downlink data to receive (S3-2). If thereis no downlink data to receive, the MSS re-enters sleep mode for anincreased sleeping interval (2*N1). Here, the sleeping intervalincreases by a specified amount (i.e., double the previous sleepinginterval) after a listening interval.

FIG. 8 illustrates a link-layer address acquisition process of a routerwhen the MSS enters sleep mode as a result of command from the networkentity. Referring to FIG. 8, the process is similar to FIG. 7. In FIG.8, however, instead of providing the MSS IP address via a requestmessage, the MSS IP address is transmitted via an information messagesince a decision to enter sleep mode is made by the network entity inthis embodiment. It is also possible to repeat the process oftransmitting the DREG-REQ message and the DREG-RSP message after the MSSreceives the DREG-CMD message to enter idle-mode. In this case, the MSSIP address would be transmitted via the DREG-REQ message.

FIG. 9 illustrates a link-layer address acquisition process of a routerwhen the MSS voluntarily enters idle-mode. In FIG. 9, the MSS transmitsthe DREG-REQ message to a first network entity in order to enteridle-mode, and in response, the first network entity transmits theDREG-CMD message to grant the MSS to enter sleep mode (S4-0). In theDREG-REQ message, the MSS includes its IP address to the first networkentity so that when the MSS is in idle-mode, the BS can respond to therouter's ARP request without having to refer to the MSS.

After the MSS has been de-registered from the first network entity (orhost BS), the first network entity broadcasts to all other BSs in thesame paging zone that the MSS has entered idle-mode (S4-1). The BSs whoreceived the broadcast then adds to its paging list the MSS information.

When the router receives an IP packet, the router transmits the ARPrequest to the host BS to determine the MAC address of the destinationIP address of the MSS (S4-2). In response, the host BS transmits an ARPresponse message to the router for the MSS since the host BS has thenecessary IP address information of the MSS (S4-3).

Upon receipt of the ARP response message, the router transmits the IPpacket to the host BS. Thereafter, the host BS transmits a pagingannouncement notifying all the BSs in the paging zone that there isdownlink data for the MSS (S4-4). After receiving the pagingannouncement, the BS having the MSS in its cell coverage area transmitsa paging message to the MSS at specified paging cycle(s) (S4-5).

FIG. 10 illustrates another embodiment of the present invention. Thisillustration shows a link-layer address acquisition process of a routerwhen the MSS enters sleep mode as a result of command from the networkentity. Referring to FIG. 10, the processes with respect tocommunicating between the MSS and network entities are similar to FIG.9. In FIG. 10, however, instead of providing the MSS IP address via arequest message, the MSS IP address can be transmitted via aninformation message since a decision to enter sleep mode is made by thenetwork entity in this embodiment. It is also possible to repeat theprocess of transmitting the DREG-REQ message and the DREG-RSP messageafter the MSS receives the DREG-CMD message to enter idle-mode. In thiscase, the MSS IP address would be transmitted via the DREG-REQ message.

In another embodiment of the present invention, the MSS makes a requestto the network entity to retain convergence sublayer information.Convergence sublayer is typically layer 2 protocols which areresponsible for gathering and formatting of higher layer information sothat it may be processed by the lower layers.

FIG. 11 illustrates another embodiment of a link-layer addressacquisition process of a router when the MSS voluntarily entersidle-mode. Referring to FIG. 11, the operation and processes of thisembodiment is similar to the processes of FIG. 9. Hence, the sameprocesses with respect to the embodiment of FIG. 9 will be excluded.

In this embodiment, the MSS transmits the DREG-REQ message to a firstnetwork entity in order to enter idle-mode, and in response, the firstnetwork entity transmits the DREG-CMD message to grant the MSS to entersleep mode (S5-0). In the DREG-REQ message, the MSS includes a requestto retain convergence sublayer (CS) information. By having the firstnetwork entity retain the CS information, the first network entity canrespond to a request from a router without having to contact the MSS inidle-mode in connection with downlink traffic. In effect, downlinktraffic can be more effectively and efficiently delivered and resourcesof the network can be better utilized. As explained above, the remainingprocesses of the embodiment is same as the processes of FIG. 9.

In addition, FIG. 12 illustrates another embodiment of the presentinvention. Here, the embodiment represents a link-layer addressacquisition process of a router when the MSS enters sleep mode as aresult of command from the network entity. Referring to FIG. 12, theprocesses with respect to communicating between the MSS and networkentities are similar to the processes of FIG. 11. In FIG. 12, however,instead of providing the MSS IP address via a request message, the MSStransmits a request message to the first network entity to retain CSinformation. This request can be transmitted via an information messageor alternatively, via a DREG-REQ message. The rest of the processes aresame as FIG. 11.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method of communicating data for performing network re-entry of amobile station (MS) in a wireless communication system, the methodcomprising: transmitting, from the MS to a network entity, aderegistration request message comprising first idle-mode retaininformation to request the network entity to retain first MS service andoperational information to expedite a future network re-entry from anidle mode; receiving, from the network entity at the MS, aderegistration command message comprising second idle-mode retaininformation indicating second MS service and operational information tobe retained by the network entity; deregistering from the network entityand entering the idle-mode responsive to the receiving of thederegistration command message; and performing a network re-entryprocedure based upon the second MS service and operational informationretained by the network entity, wherein the first idle-mode retaininformation and the second idle-mode retain information relate to atleast one of security, network address, MS capability, managementconnection identification, and network service maintenance, wherein eachof the first and the second idle-mode retain information is associatedwith a capability of the MS which is indicated by Bit#0, with securityinformation which is indicated by Bit#1, with registration informationwhich is indicated by Bit#2, and with network address which is indicatedby Bit#3.
 2. The method of claim 1, wherein the network entity is aserving base station.
 3. The method of claim 1, further comprisingtransmitting the second idle-mode retain information to a plurality ofbase stations in a paging group or to a paging controller.
 4. The methodof claim 1, wherein the de-registration request message includes arequest to initiate the idle-mode.
 5. The method of claim 1, whereinBit#0 relates to retaining of service and operational informationassociated with SBC-REQ/RSP messages, Bit#1 relates to retaining ofservice and operational information associated with PKM-REQ/RSPmessages, Bit#2 relates to retaining of service and operationalinformation associated with REG-REQ/RSP messages, and Bit#3 relates toretaining of service and operational information associated with networkaddress.